Natural philosophy

The Philosophy of nature studies the being of bodies, dealing with the very meaning of the term "body". In the course of doing so, it deals with a large number of problems. The most universal and obvious characteristic of the corporeal world is change (motion), which the Presocratic philosopher Heraclitus made into a major philosophical subject. Nature has been a fundamental problem ever since the fundamental distinction between being and becoming was pointed out.

Mechanists
The Presocratic philosopher Heraclitus argued that change affects the substance of bodies, such as the production of water by hydrogen and oxygen combining. Among the philosophers who were " Mechanists " argued that the corporeal substance is simply identified with matter, which in turn is identified with quantity or geometrical extension. Most philosophers agree that bodies are modifications of the same single substance, and that the universe is devoid of quality and energy, as space and local motion are real for them. There were a range of views from Rene Descartes's extreme views that only the soul exists, to those who believe that the body, not the soul, exists.

Dynamists
Another major school is the Dynamists, who opposed the concept of matter being a constituent of bodies. The poster child of dynamism was Gottfried Wilhelm Leibniz, who reduced corporeal subjects to his monads, which were analagous to souls. To Leibniz, extension (and sensible reality as a whole) is nothing more than an appearance or symbol, and that the corporeal world is absorbed in the spiritual.

Aristotelians
The Aristotelian philosophy recognized in corporal substance, there are two substantial principles: matter (the "first matter", or materia prima, which is not the same thing as the mechanist concept of matter), and form.

Aristotle's " first matter " does not represent the imaginable notion of extension, but represents the idea of matter in its purity, as simply that of which things are made. The understanding of matter as potentiality was an Aristotelian view. If the materia prima is that of which things are made, in itself nothing actual and capable of separate existence, the other of the two substantial principles is form.

Form is an active principal, the soul of the thing which determines the purely passive first matter. Form is imposed upon matter as a potter molds clay in resemblance of the object he has in mind. Once the sculptor sculpts his clay, it becomes something. Form makes something what it is.

Aristotle's approach became known as "hylomorphism"; corporeality (a corporeal substance) is a union of first matter (a passive principle/potentiality) with form (an active principal). Every corporeal substance is a compound of two substantial and complementary parts: one passive and wholly indeterminate (matter), and one active (form). Hylomorphism conceives of substance as a compound of matter and form. Aristotle defines an object's matter as that of which an object is made; it is a relative term. An object counts as matter relative to something else, as a clay is relative to a brick. Change is analyzed as material transformation; matter is what undergoes a change of form. A block of bronze has bronze as its matter and a block as its form, and it can change into a new form, such as a statue. According to Aristotle's theory of perception, we perceive an object by receiving its form with our sense organs.

Medieval philosophy
Medieval philosophers then used Aristotelian philosophers to distinguish between substantial forms  and accidental forms. A substance necessarily possesses at least one substantial form, and it may possess a variety of accidental forms. A substantial form of a substance consists of the object's individual properties, while accidental forms are non-essential properties that can be lost or acquired without altering the original subject's identity. The matter of a substance not made from other substances consists of prime matter.